Field of the Invention
As in most structures, so in pre-engineered metal buildings, energy savings have become more of a consideration than in the past. This emphasis on energy savings has resulted in the use of insulation boards to cover otherwise exposed framing members in such buildings.
Metal building roofs may be constructed of metal sheets which are attached to metal roof purlins. Purlins or metal framing members are installed at spaced intervals across the top of the building to lend structural support. These purlins extend in generally parallel rows from one wall to another below the roof support system or the purlins may be part of the roof support system. The roof purlins, therefore, form a series of spaced parallel strips to which insulation boards may be attached.
To save installation time, the insulation boards are sometimes long enough to span the building from one side to the other in parallel, longitudinal, edge-to-edge abutment so that a lesser number of boards will be needed to cover the purlins in installing a ceiling in the building. It is desirable that the fewest possible number of workers be used for this installation so that a simple means for installing the boards must be devised. The simplest type of components must be used to accomplish the installation.
It has been found objectionable from an aesthetic viewpoint to have exposed edges or gaps between adjacemt insulation boards so that cover strips should be provided to hide such exposed edges. In the past, adhesive strips have been placed over the gaps at adjacent edges of insulation boards but the adhesive strips have proven to be unsightly and require additional labor to install since they must be put up after the insulation boards are put in place.
If a cover member of inverted "T" configuration were used, the cover member may sag between spaced purlins and an unsightly gap may form between the cover member and the edge of the insulation boards which the cover member is designed to hide. If the inverted "T" shaped cover member is made stiff enough not to deflect, the additional material required raises its costs.
In addition, since one of the objectives of the installation is energy savings, it is desirable to have as little air movement through the ceiling as possible. Sealants or caulking should be used to prevent air movement through the system.